Maine Cosmetologist Practice Exam 2025 - Free Cosmetology Practice Questions and Study Guide

The "10-20-30" rule in hair color application specifically refers to a timing method for applying color based on the desired intensity of the result. In this context, the numbers represent the minutes of processing time depending on the type of color being applied and the level of lift or deposit desired.

For instance, this rule helps stylists determine how long to leave the hair color on based on the intensity they want to achieve. A shorter time might yield subtle results, while leaving the color on for a longer period can create a more intense and vibrant outcome. The rule serves as a guideline for professionals to ensure they achieve consistent and expected results when coloring hair, taking into account factors such as the client's natural hair color and condition.

Other options discuss different aspects of hair coloring that are not related to the application timing, such as hair porosity, shampoo usage, and dye shade selection, which are all important but don’t pertain directly to the "10-20-30" rule's focus on application timing.